Fix typo in production documentation

The directory which is created is 'stage', not 'staged'.
Mention the possibility to upgrade the play installation on version mismatch.

I just updated my project to play 2.2.1 and started it with my old 2.2.0 installation.
The error message

    This project uses Play 2.2.1!
    Update the Play sbt-plugin version to 2.2.0 (usually in project/plugins.sbt)

suggested a thing I wasn't interested in, instead it should have told me to update
my play installation. Both suggestions make sense.

One could even compare versions to give a more educated suggestion (detect upgrade/
downgrade), but because this should also support RCs and clever but still still short
suggestions/messages it's not done in a second and it's probably not worth the effort.
Merge pull request #1946 from fernandoacorreia/documentation

Fix typo in production documentation
Merge pull request #1964 from magro/fix-play-version-mismatch-msg

Mention the possibility to upgrade the play installation on version mismatch
Make `play new` consistent. Fixes #1927

* Make `play new` command require a parameter, the name of the project to create.
* If no parameter is given, the output now says "Use `play new foo` ..."
* It will not attempt to create something for `play new`
* Rewrite the detailedTopics/build/Build.md to adjust for this and provide more up-to-date, post 2.2 information.
* Adjust places in documentation where `play new` is mentioned.
Merge pull request #1963 from reid-spencer/master

Make `play new` consistent. Fixes #1927
Added validate pull request script
Merge remote-tracking branch: upstream/master